<template>
    <div>
        <router-link 
        tag='div' 
        to='/' 
        class="header-abs"
        v-show='showAbs'
        >
            <span class="iconfont header-abs-back">&#xe624;</span>
        </router-link>
        <div 
        class="header-fixed"
        v-show='!showAbs'
        :style="opacityStyle"
        >
            <router-link to='/'>
                <div class="iconfont header-fixed-back">&#xe624;</div>
            </router-link>
            景点详情
        </div>
    </div>
</template>

<script>
export default {
    name:'DetailHeader',
    data () {
        return {
            showAbs: 1,
            opacityStyle: {
                opacity: 0
            }
        }
    },
    methods: {
        handleScroll () {
            const top = document.documentElement.scrollTop
            if (top > 60 ) {
                let opacity = top / 140
                opacity = opacity > 1 ? 1 : opacity
                this.opacityStyle = {
                    opacity
                }
                this.showAbs = 0
            } else {
                this.showAbs = 1
            } 
        }
    },
    activated () {
        window.addEventListener('scroll', this.handleScroll)
    },
    deactivated () {
        window.removeEventsListener('scroll', this.handleScroll)
    }
}
</script>

<style lang="stylus" scoped>
    @import '~styles/varibles.styl'
    .header-abs
        position: absolute
        left: .2rem
        top: .2rem
        width: .8rem
        height: .8rem
        border-radius: .4rem
        line-height: .8rem
        text-align: center
        background: rgba(0, 0, 0, .8)
        .header-abs-back
            color: #fff
            font-size: .4rem
    .header-fixed
        z-index: 2
        position :fixed
        top: 0
        left: 0
        right: 0
        height : $headerHeight
        line-height : $headerHeight
        text-align :center
        color: #fff
        background : $bgColor
        font-size : .32rem
        .header-fixed-back
            top:0
            left:0
            position : absolute
            width : .64rem
            text-align :center
            font-size : .4rem
            color: #fff
</style>
